Exporting 3d object from blender cycle into unreal engine (or other engine)
You cannot simply export Cycles materials to fbx (or any game related model formats) materials. The reason for this is that Cycles uses a completely different approach to handle materials. 

Cycles material setups were designed with the idea of being able to use procedural materials with a strong focus on photorealistic rendering and animation. You can still work with textures, but the main setup can be still considered as procedural, especially when using emission, glossy, transparency and translucency. 

Game engines still use textures and uv-maps to project those textures on the models. Specific material setups like emission often need to be done in the Game Engine's material editor.

The procedure to go from a cycles material to a material that is (halfway) ready to be used in a game engine involves unwrapping your model and its submeshes and then baking the different texture maps for your material. This would be at least the diffuse map (pure color, no shadows, no light values). Additional texture maps could be normal maps, specularity maps and ambient occlusion maps.